1. Field of the Invention
The present invention relates to a flat panel display apparatus, and in particular to a barrier structure for a PDP(Plasma Display Panel) and a fabrication method thereof which are capable of increasing a discharge efficiency by obtaining a larger discharge space.
2. Description of the Background Art
Recently, a flat panel display apparatus such as a LCD(Liquid Crystal Display), a FED(Field Emission Display), a PDP(Plasma Display Panel), etc. is widely used. Among these flat panel display apparatuses, the PDP is most widely used and has good characteristics of an easier fabrication, a high luminance and high light emitting efficiency, a good memory function, and a wider field-of-view, so that the PDP is well adapted to a large size screen.
The structure of a conventional surface discharge AC PDP will be explained with reference to FIG. 1.
First, a certain space is formed between a front glass substrate 10 and a rear glass substrate 20, and a discharge space 30 defined by a barrier 23 is formed between the front glass substrate 10 and the rear glass substrate 30.
A plurality of parallel address electrodes A are formed on the upper surface of the rear glass substrate 20, and a dielectric layer 22 is formed on the upper surface of the rear glass substrate 20 and the upper surface of the address electrodes A.
A plurality of barriers 23 are formed on the upper surface of the dielectric layer 22 between the address electrodes A. A fluorescent layer 24 is formed on the upper surface of the dielectric layer 22 which covers both side barrier surfaces of the barriers 23 and the address electrodes A. A sustain/scan electrode Xn and a sustain electrode Yn are spaced-apart on one surface of the front glass substrate 10 in the direction perpendicular to the direction of the address electrode A. The sustain/scan electrode Xn and the sustain electrode Yn are generally formed of an ITO(Indium TiN Oxide) which is transparent so that light easily passes therethrough. Bus electrodes 13 are formed at the end portions of the sustain/scan electrode Xn and the sustain electrode Yn for applying a stable driving voltage. The bus electrode 13 is formed of an aluminum or chrome/copper/chrome layer. In addition, a PbO group dielectric layer 14 covers on the sustain/scan electrode Xn, the sustain electrode Yn, the bus electrode 13 and the front glass substrate 10, and a MgO film is coated on the bus electrode 13 and the front glass substrate 10 and acts as a protection film 15. The above-described MgO protection film protects the PbO dielectric layer from a sputtering operation of ions and provides a characteristic of a relatively high secondary electron generation coefficient when a low ion energy collides with the surface during the PDP discharge for thereby decreasing a driving and sustaining voltage of the discharge plasma.
He, Ne, Ar or a combined gas of the same and a combined gas 31 of Xe are sealingly filled in a discharge cell in the interior of the PDP of FIG. 1 surrounded by the barriers.
The space between the barriers is a discharge space 30 in which a discharge is performed.
FIG. 2 is a cross-sectional view taken along IIxe2x80x94II of FIG. 1. Since the same reference numerals in FIGS. 1 and 2 indicates the same elements, the description on the construction of FIG. 2 will be omitted.
The operation principle of the conventional PDP is as follows. Namely, when a certain driving voltage is applied between the address electrode A and sustain/scan electrode Xn, a certain cell which is located where the electrodes are crossed is selected and then a wall discharge occurs on the surface of the dielectric layer thereof. After that discharge, when a certain driving voltage is applied to the sustain electrode and sustain/scan electrode, a plasma discharge occurs on the surface of the dielectric layer, and an infrared ray generated based on the plasma discharge excites fluorescent materials of Red(R), Green(G), and Blue(B), and a visual ray of the R, G and B generated at the fluorescent materials is incident into the glass substrate via the dielectric layer and the display electrode for thereby displaying a certain character or graphic.
FIG. 3 illustrates a discharge space 30 in which a plasma discharge occurs at the PDP of FIGS. 1 and 2. As shown therein, a dielectric later 22 is formed on the rear glass substrate 20, and a barrier 23 is formed on the dielectric layer 22 for separating each discharge cell. The size of the discharge space 30 is determined based on the height of the barrier 23 and a distance between the barriers 23. In the conventional PDP, the height of the barrier is about 150 xcexcm, and the width(a distance between the barriers, namely, the size of the bottom in the discharge space) is about 300 xcexcm. In addition, a fluorescent layer 24 having a thickness of about 20 xcexcm is formed on the wall of the barrier 23 and the upper surface of the dielectric material 22. Therefore, the area of the fluorescent layer is determined based on the size of the discharge space.
In the conventional PDP having a certain size of the discharge space as shown in FIG. 3, the discharge efficiency is about 11 m/w which is relatively low compared to the light emitting efficiency(51 m/w) of the Braun Tube.
Therefore, it is very important to improve the light emitting efficiency in the field of the PDP.
Here, the light emitting efficiency is obtained based on the following Equation 1.
F=Kxcex7xe2x80x94qhvxcex3"PHgr"xe2x80x83xe2x80x83Equation 1
where F represents a light speed of output visual light, K represent an area of the surface of the fluorescent material in the discharge space, _represents a discharge cell escape efficiency of the visual light from the fluorescent material, xcex7q represents an quantum efficiency of the fluorescent material hv represents an energy of the visual light, xcex3 represents a sensitivity(1 m/W), and "PHgr" represents a speed of the visual light which reach at the unit surface of the discharge cell. Therefore, as seen in Equation 1, the discharge efficiency is determined based on the area of the fluorescent material and the amount of the infrared ray. The area of the fluorescent material may be increased by increasing the discharge efficiency.
The area of the fluorescent material may be increased by increasing the size of the discharge space, but in order to increase the discharge space in the limited panel space, the width of the barrier and the height of the barrier should be increased. However, according to the conventional barrier fabrication method such as a sand blast method, a screen printing method, an etching method, etc., it is impossible to uniformly form the barriers having a certain height above 150 m. Therefore, in order to enhance the discharge efficiency, a method for maintaining the height of the barrier at 150 m and increasing the discharge space is required.
Accordingly, it is an object of the present invention to provide a barrier structure and a fabrication method which are capable of enhancing an efficiency of a PDP.
It is another object of the present invention to provide a PDP barrier structure and a fabrication method thereof which are capable of increasing a discharge efficiency by forming a second a second barrier on the upper surface of a first barrier and increasing the surface area of the fluorescent materials.
In the PDP barrier structure according to the present invention, a two-tire structure formed of a first barrier layer formed on a substrate and having a certain height and a second barrier layer formed on the first barrier is disclosed.
To achieve the above-objects, there is provided a fabrication method for a barrier structure of a PDP according to the present invention which includes the steps of forming an insulation layer having a certain thickness on a substrate, forming a photoresist film pattern on the insulation layer, forming a first barrier layer by etching the insulation layer using the photoresist film pattern as a mask and forming a groove on the insulation layer, removing the photoresist film pattern, and forming a second barrier layer on the first barrier layer at the portion in which the photoresist film pattern is removed.
Additional advantages, objects and features of the invention will become more apparent from the description which follows.